This invention deals with improvements in the therapeutic topical application of zinc compounds to tissue and most particularly the application of zinc chloride as a fixative for necrotic, gangrenous and cancerous tissue to facilitate excision or amputation and also to promote healing of wounds.
Chemosurgery is a method of chemical fixation of diseased tissue followed by controlled surgical removal. Zinc chloride (ZnCl.sub.2) has long been used in medicine as a means to fix necrotic tissue to facilitate excision and amputation. This method has been in existence for over 50 years and its use has been best documented by Mohs application to cancers of the skin and gangrene. This work has been largely summarized in Mohs, FE, Chemosurgery in Cancer, Gangrene and Infections, Charles C. Thomas, Springfield, Ill., 1956 which is herein incorporated by reference to the extent that it is pertinent. Diabetic patients, for example, are among those afflicted with gangrene which may necessitate the amputation of toes fingers and limbs. Such amputations using conventional operating room procedures are often extremely expensive. Mohs in U.S. Pat. No. 2,344,830, which is herein incorporated by reference, disclosed paste formulations to control the area and depth of penetration of ZnCl.sub.2 in fixing tissue prior to excision. Although an improvement over procedures generally in use at the time, control of the depth of penetration and the area exposed to the ZnCl.sub.2, which are critical factors, is still difficult with Mohs' preparations. Confounding variables of skin contour, adjacent tissues and even ambient temperature and humidity contribute to the difficulty in controlling this procedure. Seepage of these preparations through wound dressings can also unintentionally expose healthy tissue of either the subject or treating provider to the fixative action of ZnCl.sub.2 thereby resulting in injury.
There is therefore a need for a means to more precisely control the area of tissue exposed and the depth of penetration in the topical application of high concentrations of ZnCl.sub.2 and a convenient and effective means to apply it to a target area and confine its activity to the desired target area without damaging healthy tissue. There is a further need for a relatively inexpensive means to facilitate amputation of gangrenous and necrotic tissue when necessary, without subjecting the patient to the trauma and expense of major surgery in an operating room setting. It has, however, been clinically observed that relatively low concentrations of zinc chloride, which penetrates the skin relatively rapidly, promotes rapid wound healing by accelerating the generation of granulation tissue even in the case of severe lesions such as those resulting from amputation. The beneficial action of zinc compounds such as zinc oxide in promoting the healing of skin lesions and wounds is well known. However, the beneficial wound healing properties of zinc oxide are limited by its slow penetration into the skin. There is yet a still further need for a means to topically administer zinc chloride in low concentrations in a manner that will promote the formation of granulation tissue and promote wound healing.